So my brother's going to Bulgaria?

My brother and his girlfriend have been together for 2 years and although they're only 17, they have a 3 month old baby girl. His girlfriends family are really quite odd and are moving to Bulgaria to 'escape Britain before it becomes a dictatorship'! She can't let her family go and so now has decided to go and has spoken my brother into this. We have bent over backwards for them and I just don't see how else I can stop them going, I don't want to keep my brother here forever I just want him to finish his education and also I'm worried for my brother's and my niece's well being. Anyone have any ideas?